As a gas turbine engine operates, airborne contaminants may accumulate on various internal components of the engine, such as the blades and the vanes of the compressor. Although the gas turbine engine system may include an inlet air filtration system, a certain degree of contaminant accumulation may be unavoidable and may depend on various environmental conditions at the site of operation. Common contaminants may include small amounts of dust and debris that pass through the inlet air filtration system as well as un-filterable hydrocarbon-based materials such as smoke, soot, grease, oil film, and organic vapors. Over time, accumulation of contaminants on the compressor blades and vanes may restrict airflow through the compressor and may shift the airfoil pattern. In this manner, such accumulation may adversely impact the performance and efficiency of the compressor and thus the overall performance and efficiency of the gas turbine engine, particularly resulting in decreased power output, increased fuel consumption, and increased operating costs.
In order to reduce contaminant accumulation, the gas turbine engine system may include a water wash system for removing contaminant particles from the compressor blades and vanes. For example, an on-line water wash system may be used to remove contaminant particles from compressor blades and vanes via a flow of water, such as demineralized water, while the gas turbine engine is operating at full speed and is loaded. The on-line water wash system may deliver the flow of water upstream of the compressor via an on-line manifold including nozzles positioned about a bellmouth of the compressor. The nozzles may create a spray mist of water droplets in this region of relatively low velocity air, and the negative pressure produced by the operating compressor may draw the spray mist into contact with the compressor blades and vanes for contaminant removal.
An off-line water wash system may be used in a similar manner to more effectively remove contaminant particles via a flow of water and detergent while the gas turbine engine is shut down or operating at a turning gear speed and is not loaded. The off-line water wash system may deliver the flow of water and detergent upstream of the compressor via an off-line manifold including nozzles positioned about a bellmouth of the compressor. In certain applications, a water wash system may be configured to operate in either an on-line mode or an off-line mode. In this manner, on-line washes may be carried out periodically to increase performance and efficiency of the gas turbine engine when the operating schedule does not permit shutdown time so as to perform a more effective off-line wash. The frequency and duration of on-line and off-line washes may vary depending on the degree of contaminant accumulation and environmental conditions at the site of operation.
Although conventional water wash systems and methods may be effective in removing contaminants from the blades and vanes of early compressor stages, such systems and methods often are less effective in removing contaminants from the blades and vanes of later compressor stages because the flow of water and detergent generally is injected about the bellmouth of the compressor. Moreover, following a wash with such systems and methods, residual amounts of the water and detergent may remain on the compressor blades and vanes, which may have an adverse impact on subsequent restart and operation of the gas turbine engine. The residual amounts of water and detergent also may facilitate surface rusting, corrosion, or subsequent accumulation of contaminants on the compressor blades and vanes. Further, the performance gain provided by conventional water wash systems and methods may of limited duration, necessitating frequent washes carried out with the water wash systems or by hand in order to maintain adequate performance, which ultimately may increase total operating costs of the gas turbine engine.
There is thus a desire for improved wash systems and methods for removing contaminants from internal components of a gas turbine engine, such as compressor blades and vanes. Specifically, such improved wash systems and methods should effectively remove contaminants from the blades and vanes of all compressor stages, particularly later compressor stages, while also inhibiting surface rusting, corrosion, and subsequent accumulation of contaminants on the compressor blades and vanes. Further, as compared to conventional wash systems and methods, such improved wash systems and methods should increase the duration of performance gains provided thereby and thus decrease the frequency of washes required to maintain adequate performance of the gas turbine engine. Ultimately, such improved wash systems and methods should increase efficiency and performance of the gas turbine engine and decrease total operating costs.